Ammeter.



i'wrrnn STAT s GUSTAV GRABOSCII, OF BERLIN, GERMANY, ASSIGNOR TO GANS & GOLD- SOHMIDT, OF SAME PLACE.

AlVllVlETER.

SPECIFICATION forming part of Letters Patent N 0. 670,174, dated March 19, 1901.

Application filed October 12, 1900. Serial No. 32,827. (No model.)

To In whom it may concern: current will pass through the coil 1) and acts Be it known thatI, GUSTAV GRABOSCH, enrepulsively on the metal piecec mounted on gineer, of N0. 25 Reichenbergerstrasse, Berthe spindle f, causing a throw of the pointer lin, Germany, haveinvented an Improvement over the scale. The amount of this deflec- 5 in Ammeters, of which the following is a tion is a measure of the current strength. 55

specification. In order to adapt the apparatus having an The subject of the present invention is an Edison screw-thread forSiemens connections, apparatus for measuring the strength of an a metal sleeve 'm, Fig. 4, is applied to the electric current and is adapted for introducsheathing d. The sleeve m has a screwtion into the holes or sockets provided for thread above, but is smooth below. The 60 safety-fuses. Externally the new ammeter screw 11 is inserted into the sleeve on and inclosely resembles a safety-plug, being prosulated from it by a block of non-conducting vided with a metallic stem for the purpose material, but is in metallic connection with of completing the circuit. the part Z, so that the current passing th rough 15 The apparatus is shown in the accompanythe conducting-screw in the manner de- 65 ing drawings. scribed flows through the coil 1) and causes Figure 1 is an elevation, Fig. 2 a vertical deflection of the pointer. These devices can section, and Fig. 3 a face view, of the instrube employed either with or without the lead ment. Fig. shows a modification of the amfuse.

meter, in which a sleeve covers the screwed In order to protect the pointer and inter- 7ov stem. nal parts of the device, a cap 0 of transpar- The apparatus consists of a spool a of inent materialsuch as celluloid, mica, glass, sulating material, such as wood or the like, or the likemay be fitted over the whole aphaving the shape of a safety-plug and being paratus. The cap may also be made of opaque wound with wire I). The lower part or stem material, having a transparent top through of the spool is provided with a screw-thread which to observe the pointer.

0, covered in the usual manner with a metal I claimsheathing d. The spool to is bored centrally, 1. An ammeter, comprising a centrallyand into the bore a small cylinder 2, closed bored bobbin of plug form, the bobbin-coils,

0 below, is inserted. The cylinder contains a a spindle mounted in said boring, a metal spindle f, carrying a long metal piece g, propiece secured to said spindle, a spring-actuvided above with a pointer h and spiral 2'. ated pointer mounted on said spindle and de- On rotation of the spindle the spring is comfiected on a current passing through the bobpressed and on cessation of the motive force bin-coils, a scale for said pointer and means 35 it expands, bringing the pointer back to its for connecting the respective ends of the boboriginal position. bin-coil to the poles of the circuit, in such On the top of the spool a ascale is arranged, manner that when the amineter is connected as shown in Fig. 3, over which the pointer h in the circuit by being inserted into asafetymoves. In the bore of the spool is also conplug hole, the current passes through its coil 40 t ained the lead strip is, connected to one end and deflects the pointer, substantially as de- Z) of the coil 19 by means of an intermediate scribed. block, which can be connected to one pole of 2. An ammeter, comprising a eentrallythe circuit. The other end 5 of the coil 1) is bored bobbin of plug form, the bobbin-coils, connected with the metallic sheathing cl, a spindle mounted in said boring, a metal 5 whereby it can be connected with the other piece secured to said spindle, a spring-actupole of the circuit. It now the apparatus is ated pointer mounted on said spindle and deinserted as a plug in the circuit, the latter, tlected on a current passing through the bobhitherto interrupted, will now be closed, the bin-coils, a scale for said pointer, a safetymetal block Z and metal sheathing cl making fuse located in said boring and connecting 50 contact with the poles of the circuit. The one end of the bobbin-coil to one pole of the circuit, and means for connecting the other end of the bobbin-coil with the other pole of the circuit, substantially as described.

3. An ammeter, comprising a centrallybored bobbin of plug form having a screwthreaded stem, the bobbin coils, a spindle mounted in said boring, a metal piece secured to said spindle, a spring-actuated pointer mounted on said spindle and deflected. on a current passing through the bobbin-coils, a scale for said pointer, a metallic piece secured to the base of the bobbin and connected to one end of the bobbin-coil, and a metallic sheathing on the said bobbin-stem connected to the other end of said coil, substantially as described.

4. An ammeter, comprising a centrallybored bobbin of plug form having a screwthreaded stem, the bobbin -coils, a spindle mounted in said boring, a metal piece secured to said spindle, a spring-actuated pointer mounted on said spindle and deflected on a current passing through the bobbin-coils, a scale for said pointer, a metallic piece secured to the base of the bobbin and connected to one end of the bobbin-coil, and a metallic sheathing on the said bobbin-stem connected to the other end of said coil, in combination with a metallic sleeve adapted to screw over said stem and having a smooth lower part, and a screw secured to, but insulated from said sleeve, and making electrical contact with said metallic base-piece of the bobbin, substantially as described.

In testimony that I claim the foregoing as my invention I have signed my namein presence of two subscribing witnesses.

GUSTAV GRABOSOH.

Witnesses:

HENRY HASPER, WOLDEMAR HAUPT'. 

